Fragile X mental retardation protein protects against tumour necrosis factor-mediated cell death and liver injury

Exploring the molecular mechanisms network of breast cancer by multi-omics analysis

BACKGROUND

Breast cancer (BC), the most prevalent malignancy in women globally, still lacks comprehensive research on its molecular targets and necessitates further investigation into the underlying molecular mechanisms driving its initiation and progression.

METHODS

The GSE20685 Series Matrix File downloaded from the Gene Expression Omnibus database was divided into a high-risk group (n = 49) and a low-risk group (n = 278) to construct the co-expression network.

RESULTS

Four hub genes were identified based on the Weighted Gene Co-expression Network Analysis. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional enrichment analyses were performed. Hub gene immune infiltration was investigated using the Tumor Immune Estimation Resource database, and CD4+ T cell expression levels were substantially correlated with hub gene expression. Based on the CancerRxGene database (Genomics of Drug Sensitivity in Cancer database), it was found that the hub genes were highly sensitive to common chemotherapy drugs such as AKT inhibitor VIII and Erlotinib. The expression of Secreted Frizzled-Related Protein 1, melanoma-inhibiting activity (MIA), and Keratin 14 was related to tumor mutation burden, and the expression of MIA also affected the microsatellite instability of the tumor. This study employs multi-omics analysis to investigate the molecular network associated with the prognosis of BC, highlighting its intricate connection with the immune microenvironment.

CONCLUSION

These findings pinpoint four crucial genes in BC progression, offering targets for further research and therapy. Their connections to immune infiltration and chemotherapy sensitivity underscore complex interactions in the tumor microenvironment.

G-Quadruplex RNA Based PROTAC Enables Targeted Degradation of RNA Binding Protein FMRP for Tumor Immunotherapy

Fragile X mental retardation protein (FMRP), an RNA binding protein (RBP), is aberrantly hyper-expressed in human tumors and plays an essential role in tumor invasion, metastasis and immune evasion. However, there is no small-molecule inhibitor for FMRP so far. In this study, we developed the first FMRP-targeting degrader based on PROteolysis TArgeting Chimera (PROTAC) technology and constructed a heterobifunctional PROTAC through linking a FMRP-targeting G-quadruplex RNA (sc1) to a von Hippel-Lindau (VHL)-targeting ligand peptide (named as sc1-VHLL). Sc1-VHLL specifically degraded endogenous FMRP via ubiquitination pathway in both mouse and human cancer cells. The FMRP degradation significantly changed the secretion pattern of cancer cells, resulting in higher expression of pro-inflammatory cytokine and smaller amounts of immunomodulatory contents. Furthermore, sc1-VHLL, when encapsulated into ionizable liposome nanoparticles (LNP), efficiently targeted tumor site and degraded FMRP in cancer cells. In CT26 tumor-bearing mouse model, FMRP degradation within tumors substantially promoted the infiltration of lymphocytes and CD8 T cells and reduced the proportion of Treg cells, reshaping the proinflammatory tumor microenvironment and accordingly transforming cold tumor into hot tumor. When combined with immune checkpoint blockade (ICB) therapy, sc1-VHLL based treatment remarkably inhibited the tumor growth.

FMRP protects breast cancer cells from ferroptosis by promoting SLC7A11 alternative splicing through interacting with hnRNPM

Ferroptosis is a unique modality of regulated cell death that is driven by iron-dependent phospholipid peroxidation. N6-methyladenosine (m6A) RNA modification participates in varieties of cellular processes. However, it remains elusive whether m6A reader Fragile X Mental Retardation Protein (FMRP) are involved in the modulation of ferroptosis in breast cancer (BC). In this study, we found that FMRP expression was elevated and associated with poor prognosis and pathological stage in BC patients. Overexpression of FMRP induced ferroptosis resistance and exerted oncogenic roles by positively regulating a critical ferroptosis defense gene SLC7A11. Mechanistically, upregulated FMRP catalyzes m6A modification of SLC7A11 mRNA and further influences the SLC7A11 translation through METTL3-dependent manner. Further studies revealed that FMRP interacts with splicing factor hnRNPM to recognize the splice site and then modulated the exon skip splicing event of SLC7A11 transcript. Interestingly, SLC7A11-S splicing variant can effectively promote FMRP overexpression-induced ferroptosis resistance in BC cells. Moreover, our clinical data suggested that FMRP/hnRNPM/SLC7A11 expression were significantly increased in the tumor tissues, and this signal axis was important evaluation factors closely related to the worse survival and prognosis of BC patients. Overall, our results uncovered a novel regulatory mechanism by which high FMRP expression protects BC cells from undergoing ferroptosis. Targeting the FMRP-SLC7A11 axis has a dual effect of inhibiting ferroptosis resistance and tumor growth, which could be a promising therapeutic target for treating BC.

Bile acid-induced IRF3 phosphorylation mediates cell death, inflammatory responses, and fibrosis in cholestasis-induced liver and kidney injury via regulation of ZBP1

BACKGROUND AND AIMS

Cell death and inflammation play critical roles in chronic tissue damage caused by cholestatic liver injury leading to fibrosis and cirrhosis. Liver cirrhosis is often associated with kidney damage, which is a severe complication with poor prognosis. Interferon regulatory factor 3 (IRF3) is known to regulate apoptosis and inflammation, but its role in cholestasis remains obscure. In this study.

APPROACH AND RESULTS

We discovered increased IRF3 phosphorylation in the liver of patients with primary biliary cholangitis and primary sclerosing cholangitis. In the bile duct ligation model of obstructive cholestasis in mice, we found that tissue damage was associated with increased phosphorylated IRF3 (p-IRF3) in the liver and kidney. IRF3 knockout ( Irf3-/- ) mice showed significantly attenuated liver and kidney damage and fibrosis compared to wide-type mice after bile duct ligation. Cell-death pathways, including apoptosis, necroptosis, and pyroptosis, inflammasome activation, and inflammatory responses were significantly attenuated in Irf3-/- mice. Mechanistically, we show that bile acids induced p-IRF3 in vitro in hepatocytes. In vivo , activated IRF3 positively correlated with increased expression of its target gene, Z-DNA-Binding Protein-1 (ZBP1), in the liver and kidney. Importantly, we also found increased ZBP1 in the liver of patients with primary biliary cholangitis and primary sclerosing cholangitis. We discovered that ZBP1 interacted with receptor interacting protein 1 (RIP1), RIP3, and NLRP3, thereby revealing its potential role in the regulation of cell-death and inflammation pathways. In conclusion.

CONCLUSIONS

Our data indicate that bile acid-induced p-IRF3 and the IRF3-ZBP1 axis play a central role in the pathogenesis of cholestatic liver and kidney injury.

Fragile X Messenger Ribonucleoprotein Protein and Its Multifunctionality: From Cytosol to Nucleolus and Back

Silencing of the fragile X messenger ribonucleoprotein 1 (FMR1) gene and a consequent lack of FMR protein (FMRP) synthesis are associated with fragile X syndrome, one of the most common inherited intellectual disabilities. FMRP is a multifunctional protein that is involved in many cellular functions in almost all subcellular compartments under both normal and cellular stress conditions in neuronal and non-neuronal cell types. This is achieved through its trafficking signals, nuclear localization signal (NLS), nuclear export signal (NES), and nucleolar localization signal (NoLS), as well as its RNA and protein binding domains, and it is modulated by various post-translational modifications such as phosphorylation, ubiquitination, sumoylation, and methylation. This review summarizes the recent advances in understanding the interaction networks of FMRP with a special focus on FMRP stress-related functions, including stress granule formation, mitochondrion and endoplasmic reticulum plasticity, ribosome biogenesis, cell cycle control, and DNA damage response.

Identification of necroptosis-related features in diabetic nephropathy and analysis of their immune microenvironent and inflammatory response

Background: Diabetic nephropathy (DN) was considered a severe microvascular complication of diabetes, which was recognized as the second leading cause of end-stage renal diseases. Therefore, identifying several effective biomarkers and models to diagnosis and subtype DN is imminent. Necroptosis, a distinct form of programmed cell death, has been established to play a critical role in various inflammatory diseases. Herein, we described the novel landscape of necroptosis in DN and exploit a powerful necroptosis-mediated model for the diagnosis of DN. Methods: We obtained three datasets (GSE96804, GSE30122, and GSE30528) from the Gene Expression Omnibus (GEO) database and necroptosis-related genes (NRGs) from the GeneCards website. Via differential expression analysis and machine learning, significant NRGs were identified. And different necroptosis-related DN subtypes were divided using consensus cluster analysis. The principal component analysis (PCA) algorithm was utilized to calculate the necroptosis score. Finally, the logistic multivariate analysis were performed to construct the necroptosis-mediated diagnostic model for DN. Results: According to several public transcriptomic datasets in GEO, we obtained eight significant necroptosis-related regulators in the occurrence and progress of DN, including CFLAR, FMR1, GSDMD, IKBKB, MAP3K7, NFKBIA, PTGES3, and SFTPA1 via diversified machine learning methods. Subsequently, employing consensus cluster analysis and PCA algorithm, the DN samples in our training set were stratified into two diverse necroptosis-related subtypes based on our eight regulators' expression levels. These subtypes exhibited varying necroptosis scores. Then, we used various functional enrichment analysis and immune infiltration analysis to explore the biological background, immune landscape and inflammatory status of the above subtypes. Finally, a necroptosis-mediated diagnostic model was exploited based on the two subtypes and validated in several external verification datasets. Moreover, the expression level of our eight regulators were verified in the singe-cell level and glomerulus samples. And we further explored the relationship between the expression of eight regulators and the kidney function of DN. Conclusion: In summary, our necroptosis scoring model and necroptosis-mediated diagnostic model fill in the blank of the relationship between necroptosis and DN in the field of bioinformatics, which may provide novel diagnostic insights and therapy strategies for DN.

Therapeutic inhibition of miR-155 attenuates liver fibrosis via STAT3 signaling

Most chronic liver diseases progress to liver fibrosis, which, when left untreated, can lead to cirrhosis and hepatocellular carcinoma. MicroRNA (miRNA)-targeted therapeutics have become attractive approaches to treat diseases. In this study, we investigated the therapeutic effect of miR-155 inhibition in the bile duct ligation (BDL) mouse model of liver fibrosis and evaluated the role of miR-155 in chronic liver fibrosis using miR-155-deficient (miR-155 knockout [KO]) mice. We found increased hepatic miR-155 expression in patients with cirrhosis and in the BDL- and CCl4-induced mouse models of liver fibrosis. Liver fibrosis was significantly reduced in miR-155 KO mice after CCl4 administration or BDL. To assess the therapeutic potential of miR-155 inhibition, we administered an rAAV8-anti-miR-155 tough decoy in vivo that significantly reduced liver damage and fibrosis in BDL. BDL-induced protein levels of transforming growth factor β (TGF-β), p-SMAD2/3, and p-STAT3 were attenuated in anti-miR-155-treated compared with control mice. Hepatic stellate cells from miR-155 KO mice showed attenuation in activation and mesenchymal marker expression. In vitro, miR-155 gain- and loss-of-function studies revealed that miR-155 regulates activation of stellate cells partly via STAT3 signaling. Our study suggests that miR-155 is the key regulator of liver fibrosis and might be a potential therapeutic target to attenuate fibrosis progression.

Titanium dioxide nanoparticles: revealing the mechanisms underlying hepatotoxicity and effects in the gut microbiota

Numerous studies in recent years have questioned the safety of oral exposure to titanium dioxide nanoparticles (TiO2 NPs). TiO2 NPs are not only likely to accumulate in the gastrointestinal tract, but they are also found to penetrate the body circulation and reach distant organs. The liver, which is considered to be a target organ for nanoparticles, is of particular concern. TiO2 NPs accumulate in the liver and cause oxidative stress and inflammatory reactions, resulting in pathological damage. The impact of TiO2 NPs on liver aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was studied using a meta-analysis. According to the findings, TiO2 NPs exposure can cause an elevation in AST and ALT levels in the blood. Furthermore, TiO2 NPs are eliminated mostly through feces, and their lengthy residence in the gut exposes them to microbiota. The gut microbiota is also dysbiotic due to titanium dioxide's antibacterial capabilities. This further leads to changes in the amount of microbiota metabolites, which can reach the liver with blood circulation and trigger hepatotoxicity through the gut-liver axis. This review examines the gut-liver axis to assess the effects of gut microbiota dysbiosis on the liver to provide suggestions for assessing the gut-hepatotoxicity of TiO2 NPs.

The value of NLR versus MLR in the short-term prognostic assessment of HBV-related acute-on-chronic liver failure

BACKGROUND

Systemic inflammation is associated with the development and progression of hepatitis B-associated acute-on-chronic liver failure (HBV-ACLF). The neutrophil-to-lymphocyte ratio (NLR) has been reported to be a prognostic biomarker in patients with HBV-ACLF. However, the role of the monocyte-to-lymphocyte ratio (MLR) as a prognostic inflammatory biomarker in multiple diseases is rarely mentioned in HBV-ACLF.

METHODS

We included a total of 347 patients with HBV-ACLF who met the definition of the Chinese Guidelines for the Diagnosis and Treatment of Liver Failure (2018 edition). Among them, 275 cases were included retrospectively, and 72 cases were collected prospectively. Clinical characteristics and laboratory examination data were collected from medical records within 24 h after diagnosis to calculate MLR and NLR levels, and lymphocyte subpopulation counts were collected in prospectively included patients.

RESULTS

Of the 347 patients with HBV-ACLF, 128 patients in the non-surviving group had a mean age of 48.87 ± 12.89 years; 219 patients in the survival group had a mean age of 44.80 ± 11.80 years and a combined 90-day mortality rate of 36.9%. The median MLR was higher in the non-survivors than in the survivors (0.690 vs 0.497, P < 0.001). MLR values were significantly associated with 90-day mortality in HBV-ACLF (OR 6.738; 95% CI 3.188-14.240, P < 0.001). The AUC for the predictive power of the combined MLR and NLR analysis for HBV-ACLF was 0.694, and the calculated MLR threshold was 4.495. In addition, in the analysis of peripheral blood lymphocyte subsets in HBV-ACLF, a significant decrease in the number of circulating lymphocytes was found in HBV-ACLF patients in the non-surviving group (P < 0.001), with a predominant decrease in the number of CD8 + T cells and no significant difference in the number of CD4 + T cells, B cells or NK cells.

CONCLUSION

Increased MLR values are associated with 90-day mortality in patients with HBV-ACLF, and the MLR may serve as a potential prognostic indicator for patients with HBV-ACLF. Decreased CD8 + T-cell counts may be associated with poor survival in patients with HBV-ACLF.

Necroptosis in the developing brain: role in neurodevelopmental disorders

Cell death is vital to various organismal developmental processes including brain development. Apoptosis, the most recognized programmed cell death, has been linked to several developmental processes and implicated in pruning cells to provide the ultimate tissue integrity. However, more recently, other forms of non-apoptotic programmed cell death have been identified, of which necroptosis is of predominant interest. Necroptosis is a regulated form of necrosis, activated under apoptotic-deficient conditions. Tumour necrosis factor (TNF) is a major activator of necroptosis, and the process is mediated by several kinases including receptor-interacting protein kinase (RIPK) and mixed lineage kinase domain-like protein (MLKL). Potential roles for necroptosis during brain development have been muted. Necroptosis has been implicated in mediating neurological disorders, and contributing to the severity of these disorders. Here we will review the literature on the role of necroptosis in neurodevelopment, summarizing its molecular mechanisms and highlighting potential implications for disorders of the developing brain.

The role of ADAM17 during liver damage

A disintegrin and metalloprotease (ADAM) 17 is a membrane bound protease, involved in the cleavage and thus regulation of various membrane proteins, which are critical during liver injury. Among ADAM17 substrates are tumor necrosis factor α (TNFα), tumor necrosis factor receptor 1 and 2 (TNFR1, TNFR2), the epidermal growth factor receptor (EGFR) ligands amphiregulin (AR) and heparin-binding-EGF-like growth factor (HB-EGF), the interleukin-6 receptor (IL-6R) and the receptor for a hepatocyte growth factor (HGF), c-Met. TNFα and its binding receptors can promote liver injury by inducing apoptosis and necroptosis in liver cells. Consistently, hepatocyte specific deletion of ADAM17 resulted in increased liver cell damage following CD95 stimulation. IL-6 trans-signaling is critical for liver regeneration and can alleviate liver damage. EGFR ligands can prevent liver damage and deletion of amphiregulin and HB-EGF can result in increased hepatocyte death and reduced proliferation. All of which indicates that ADAM17 has a central role in liver injury and recovery from it. Furthermore, inactive rhomboid proteins (iRhom) are involved in the trafficking and maturation of ADAM17 and have been linked to liver damage. Taken together, ADAM17 can contribute in a complex way to liver damage and injury.

Selenium-deficient diet induces necroptosis in the pig brain by activating TNFR1 via mir-29a-3p

Selenium (Se) deficiency is one of the crucial factors related to nervous system disease and necroptosis. MicroRNAs (miRNAs) play vital roles in regulating necroptosis. However, the mechanism of Se deficiency-induced necroptosis in the pig brain tissue and the role that miRNAs play in this process are unclear. Therefore, in this study, in vitro and pig models of Se deficiency were replicated, and electron microscopy, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assays were performed. The results showed that brain cells typically undergo necrotic changes, and that Se deficiency suppresses mir-29a-3p, which increases the levels of TNFRSF1A (TNFR1). Subsequently, a distinct increase in the necroptosis markers (RIPK1, RIPK3, and MLKL) and an evident decrease in caspase 8 was observed. And the expression of 10 selenoproteins was decreased. Moreover, the in vitro experiments showed that the expression of mir-29a-3p decreased as the Se content in the medium decreased and the application of an mir-29a-3p inhibitor increased the number of necrotic cells and the accumulation of ROS, and these effects were inhibited by necrostatin-1 (Nec-1) and N-acetyl-cysteine (NAC), respectively. Taken together, we proved that Se deficiency induced necroptosis both in vitro and in vivo through the targeted regulation of TNFR1 by mir-29a-3p in the pig brain.

Characteristics of Peripheral Lymphocyte Subsets in Patients With Acute-On-Chronic Liver Failure Associated With Hepatitis B

Background and Aims: Acute-on-chronic liver failure (ACLF) is a rare, but dramatic clinical syndrome. There is substantial evidence suggesting that immunity-mediated inflammation plays an important role in HBV-ACLF. Our aim was to characterize the proportion and cell counts of peripheral blood lymphocyte subsets in acute-on-chronic liver failure patients caused by HBV infection.

Methods: One hundred and seventeen patients were enrolled in this study, including those with HBV-related ACLF (HBV-ACLF; n = 70), and HBV related non-ACLF patients (HBV non-ACLF; n = 47). Demographics, clinical and laboratory data at hospital admission were retrospectively analyzed. The percentage and cell count of peripheral lymphocyte subsets were evaluated by flow cytometry. Comparison analysis was performed by t-test or non-parametric Mann–Whitney U-test. Actuarial probabilities of death were calculated by the Kaplan-Meier method.

Results: Both circulating lymphocyte count and lymphocyte percentage were significantly reduced in patients with HBV-ACLF (P < 0.001). The CD8⁺ T cell, CD4⁺ T cell, and CD16⁺CD56⁺ NK cell counts were significantly decreased in HBV-ACLF. Consistently, flow cytometric analysis showed that CD8⁺ T cell counts were significantly decreased in non-survivors, while no significant differences were found in CD4⁺ T cell, CD19⁺ B cell, or CD56⁺CD16⁺ NK cell counts. Furthermore, the group with the lower CD8⁺ T cell count displayed a significantly higher mortality rate compared with the group with the higher CD8⁺ T cell count.

Conclusions: The abnormal prevalence of lymphocyte subsets may be important in the pathogenesis of HBV-ACLF. The decrease in CD8⁺ T cell counts may be related to poor survival in HBV-ACLF patients.

NFATc4 mediates ethanol-triggered hepatocyte senescence

BACKGROUND

Hepatocyte senescence is a core event that mediates the occurrence and development of alcoholic liver disease. Nuclear factor of activated T-cells 4 (NFATc4) is a key driver of nonalcoholic steatohepatitis. However, little was known about the implication of NFATc4 for alcoholic liver disease. This study was aimed to investigate the role of NFATc4 in hepatocyte senescence and further elucidate the underlying mechanism.

METHODS

Real-time PCR, Western blot, immunofluorescence staining, and enzyme-linked immunosorbent assay were performed to explore the role of NFATc4 in hepatocyte senescence.

RESULTS

NFATc4 was induced in ethanol-incubated hepatocytes. NFATc4 knockdown recovered cell viability and reduced the release of aspartate transaminase, alanine transaminase, and lactic dehydrogenase from ethanol-incubated hepatocytes. NFATc4 knockdown protected mice from alcoholic liver injury and inflammation. NFATc4 knockdown counteracted ethanol-induced hepatocyte senescence, evidenced by decreased senescence-associated β-galactosidase positivity and reduced p16, p21, HMGA1, and γH2AX, which was validated in in vivo studies. Peroxisome proliferator-activated receptor (PPAR)γ was inhibited by NFATc4 in ethanol-treated hepatocytes. PPARγ deficiency abrogated the inhibitory effects of NFATc4 knockdown on hepatocyte senescence, oxidative stress, and hepatic steatosis in mice with alcoholic liver disease.

CONCLUSIONS

This work discovered that ethanol enhanced NFATc4 expression, which further triggered hepatocyte senescence via repression of PPARγ.

The Fragile X Mental Retardation Protein Regulates RIPK1 and Colorectal Cancer Resistance to Necroptosis

BACKGROUND & AIMS

The fragile X mental retardation protein (FMRP) affects multiple steps of the mRNA metabolism during brain development and in different neoplastic processes. However, the contribution of FMRP in colon carcinogenesis has not been investigated.

METHODS

FMR1 mRNA transcript and FMRP protein expression were analyzed in human colon samples derived from patients with sporadic colorectal cancer (CRC) and healthy subjects. We used a well-established mouse model of sporadic CRC induced by azoxymethane to determine the possible role of FMRP in CRC. To address whether FMRP controls cancer cell survival, we analyzed cell death pathway in CRC human epithelial cell lines and in patient-derived colon cancer organoids in presence or absence of a specific FMR1 antisense oligonucleotide or siRNA.

RESULTS

We document a significant increase of FMRP in human CRC relative to non-tumor tissues. Next, using an inducible mouse model of CRC, we observed a reduction of colonic tumor incidence and size in the Fmr1 knockout mice. The abrogation of FMRP induced spontaneous cell death in human CRC cell lines activating the necroptotic pathway. Indeed, specific immunoprecipitation experiments on human cell lines and CRC samples indicated that FMRP binds receptor-interacting protein kinase 1 (RIPK1) mRNA, suggesting that FMRP acts as a regulator of necroptosis pathway through the surveillance of RIPK1 mRNA metabolism. Treatment of human CRC cell lines and patient-derived colon cancer organoids with the FMR1 antisense resulted in up-regulation of RIPK1.

CONCLUSIONS

Altogether, these data support a role for FMRP  in controlling RIPK1 expression and necroptotic activation in CRC.